The transaction, coupled with Chinatrust Commercial Bank, Ltd.’slease at the building, which was also just announced, raises occupancy at the 463,000-square-foot, 39-story boutique office building, located two blocks from Grand Central Terminal, to 98 percent, according to a statement from SL Green.

“Leasing activity at the building accelerated at the end of 2012,” said Steven Durels, director of leasing at SL Green, adding that “comprehensive redevelopment and value-oriented rents have attracted several new tenants to the building.”

521 Fifth Avenue

The firm took 21,677 square feet in the 10-year deal to occupy the entire 5th floor, while Chinatrust Commercial Bank, Ltd. signed a 20,987-square foot, 15-year lease for the entire 11th floor. The firms join a list of tenants within the building that includes Royal Healthcare, Lebenthal Holdings, Starz Media and McGraw Communications.

The legal recruiting firm, established in 1982, has offices throughout the United States, including locations in Las Vegas, Tampa, Seattle, Dallas, San Francisco, Chicago, Boston and corporate offices in Hanover, Maryland. The firm’s international offices are located in London, Hong Kong and Tokyo.

SL Green signed 54 Manhattan office leases totaling 321,622 square feet during the fourth quarter of 2012, the REIT reported late last month.